Electrically-heated vessel



Jan. 28, 1923. 1,442,910,

I A. STEINHARDT. 1

ELECTRICALLY HEATED VESSEL.

FILED AUG.29, 1921.

gag/Ll MI OrZ/Zurd'feiniardl mwm 'M/WM Patented Jan. 23, 1923.

UNITED STATES ARTHUR STEINHARDT,

OF BERLIN, GERMANY.

ELECTRICALLY-HEATED VESSEL.

Application filed August 29, 1921. Serial No. 496,526.

1 0 all whom. it may concern:

Be it known that I, ARTHUR STEINHARDT, a citizen of Germany, andresiding at Berlin, Germany, have invented certain new and usefulImprovements in Electrically-Heated Vessels (for which I have filedapplications in Germany, September 11, 1919, Patent No. 340,211;Czecho-Slovakia, July 26, 1921; France, July 28, 1921, and GreatBritain, July 28, 1921), of which the following is a specification.

My invention relates to improvements in electrically heated vessels madefrom ceramic matter and in-the method of making the same, and theobjects of the improvements are to provide a vessel in which the heatingconductor is entirely confined in ceramic matter, in which the water hasno access to the conductor and surrounding parts, in which the conductoris embedded in a reliable insulation so as to avoid loss of energy andshort-circuits, in which the conductor is not injured by the bakingprocess, and in which the ceramic matter embedding the conductor is notinjured by nonuniform expansion by heat. VV'ith these and other objectsin view my invention consists in manufacturing the body of the vesselfrom suitable ceramic matter of ordinary composition, baking the same athigh temperature, applying the conductor thereon, covering the conductorby means of ceramic matter similar as to its composition and physicalproperties to the matter from which the body is made but having a largerproportion of a fluxing medium added thereto for reducing the melting orfusing temperature to a point which is not injurious to the conductor,and finally again baking the vessel with the conductor and ceramiccoating applied thereto at a temperature Fig. 2, is a vertical sectionshowin another form.

Referring at first to the example shown in Big. 1, my improved vesselconsists of a body a of ceramic matter having at the lower part of itsside wall a portion 6 of reduced diameter, an electrical conductor dcelled around said portion of reduced diameter and made from a suitablematerial adapted to transform the electric energv into heat, twoterminals 6 connected respedtively to the ends of the conductor d andfitted in a block 7 of insulating material, a collar 9 likewise ofceramic matter filling the groove around the portion Z) of reduceddiameter and covering the electric conductor (1, and a handle 2' madeintegral with the body a. The body a consists of a suitable ceramicmatter of known or preferred composltlon, such as porcelain, clay, andthe like, and composed for example of matter such as kaolin, feldspar,quartz, etc. The collar 9 consists of a matter which has a similarcomposition as the body a, which however has a larger proportion of aflux mg medium of media added thereto such as oxids of magnesium,sodium, lead, boron and a small amount of chlorid of sodium and waterglass. Such media are adapted considerably to change the melting orfusing properties of the composition the fusing temperature corresonding for example to 0 12 or 0 13 of egers scale (that is to say, aboutor 835 Centigrade respectively) and in addition they have the functlonto impart to the mass being baked a degree of shrinkage and acoefficient of expansion which nearly correspond to the physicalproperties of the mass from which the body is made, and which in thefinished vessel impart to the parts thereof substantially the samecoetficient of expansion. It will therefore be understood that thecomposition of the matter g depends in each case on the composition ofthe mass a and the physical properties thereof and and more particularlyon the shrinkage, coefficient of expansion, and the fusing temperature.In one example the body a is composed of 48% clay matter, 40% quartz,and 12% feldspar. If the conductor d consists of the alloy known in thetrade under the name of nichrom, a suitable composition of theprotecting layer is: I

0.1 Na,() 0.3 K 0 0.4 Mg() 0.2 Ca@ 0.4 A1 0 2.6 Sit),

the like at the temperature required for fusing the matter. Thistemperature is such as is necessary in each case according to thecharacter of the composition. and in case of porcelain it is say l380(3., which temperature would of course be destructive to a conductor ofany composition. Thereafter the body a is glazed internally andexternally preferably however with exception of the outer surface of theportion b of reduced diameter. Now the conductor d is coiled around theportion 1; the surface of which is preferably formed with a helicalgroove h for embedding the conductor therein, and the conductor isconnected to the terminals 6 embedded in the block f. Finally theportion of'reduced diameter is filled out with a ceramic matter 9 havingin the present example the composition stated above, and the vessel isagain brought into a kiln and heated to a temperature which is far belowthe temperature at which the body has before been baked, for instance to835 or 855 centigrade, as referred to above. By the mass 9 the groovearound the portion of reduced diameter is preferably filled out to thediameter of the'body a, and the mass should not be too wet, a statesimilar to resin being preferred in most cases. I have found that themass adheres very well to the non-glazed surface of the portion b, andthat after baking the masses a and-g are practically an integral body.In some cases the outer surface of the mass 9 is glazed. In amodification of the invent-ion the first glazing of the body a 15omitted and the complete vessel is glazed after baking the mass 9.

In the construction shown in Fig. 2 the conductor d is embedded in aspiral'groove k formed in the bottom 0 of the body a and the protectivemass is likewise applied to the said .bottom. The body is .formed at itsbottom with a. flange k, The

Fig 1.

referably the terminals 6 are displaced relatively to the handle 71 atan angle of 90, and they are placed horizontally 'one beside the other,the arrangement shown in the figures being made only for convenience ofillustration.

In addition to the advantages stated above it will be noted that thecost of manufacture is low, because in any case the use 'of expensivemetals such as nickel, copper, and their alloys is reduced to a minimum,and it is entirely avoided in such cases in which the conductor (1consists of a siliconcarbon compound such as products known under thetrade names of silit, silundum, carborundum, and the like.- Finally, thecost of manufacture is materially reduced as compared to vessels madefrom metal.

While in describing the invention reference has been made to particularexamples embodying the same, I wish it to be understood that myinvention is not limited to the forms of'heating apparatus and to themethods described and that various changes may be made without departingfrom the having suitable fluxing media admixed the're-- to and baked atreduced temperature.

2. The herein described electrical heating apparatus, which consists ofa body made from ceramic matter of high fusing temperature and baked athigh temperature, an

electric conductor, and a protective layer of ceramic matter for saidconductor having a composition similar to that of the body and havingits fusing temperature reduced'by having suitable fiuxing media admixedthere to and baked at reduced temperature and having a shrinkingproperty and coeflicient of expansion similar to those of the matter ofthe body.

3. The herein described method of manufacturing electrical heatingapparatus, which consists in moulding a body from ceramic matter, bakingsaid body, applying thereto an electric conductor and ceramic matterembedding the same and consisting of a compositionsimilar to that fromwhich the body is made and having added thereto a suitable fluxingmedium adapted to reduce its fusing temperature to a point whichis notinjurious ramic matter.

4. The herein described method of manufacturing electrical heatingapparatus, which consists in moulding a body from ceramic matter, bakingsaid body, applying thereto an electric conductor and ceramic matterembedding the same and consisting of a composition similar to that fromwhich the body is made and having added thereto a suitable fluxingmedium adapted to reduce its fusing temperatureto a point which is notinjurious to the conductor and having a coefficient of expansion similarto that of the body, and

baking the body-and the ceramic matter applied thereto at a temperaturesuflicient to fuse the applied ceramic matter.

5. Theherein described method of manufacturing electrical heatingapparatus, which consists in mouldinga body from ceramic mattercontaining kaolin, quartz, and feldspar, baking said body, applyingthereto an electric conductor and ceramic matter embedding the same andconsisting of a composition containing kaolin, quartz, feldspar, andoxids of magnesium, sodium, lead, and boron, the amount of such fluxingmedia being suflicient to reduce the fusing temper ature to a pointwhich is not injurious to the conductor, and baking the body and theceramic matter applied thereto at a temperature suflicient to fuse theapplied ceramic matter.

In testimony whereof I hereunto aflix my signature in the presence oftwo witnesses.

ARTHUR STEIN HARDT.

